Energy Efficient Windows – Double & Triple Glazed
Windows and doors are a major and long term component of any building. They are one of the main areas of heat loss in a home (15%). Correctly designed and installed windows will significantly reduce energy usage, thus drastically reducing fuel bills.
As part of the introduction of the Building Energy Rating (BER) requirement, windows will in future come with a WER (Window Energy Rating) – this is a balanced way of quantifying the energy loss across a window. It takes account of not only the heat loss inside to out, but also the heat gain from outside to inside due to solar heating effects. The ability of the windows to keep out draughts and resist condensation is also a factor. Ratings will run on a scale of A to G, in a similar way to the BER. This has been adopted in the UK and will be rolled out in Ireland. By using the information contained on the label, builders and consumers can reliably compare one product with another and make informed decisions regarding the energy performance of window products. The basic label lists the manufacturer, describes the product, includes the essential energy performance data and provides a source for additional information. The image below is an example of a cert for window certification (Note: this is a WER cert for the UK but it is being rolled out in Ireland).
Items impacting the Window Energy Rating:
Type of Glass fitted
Some glass panes contain advanced materials to act as a conductor of heat bringing solar gain into the home while insulating agents stop heat escaping.
Window Frame Design & Composition
Frames can be made from different materials such as PVC, Wood and Aluminum. These materials have different insulating properties so manufacturers may add additional insulation to the frame to improve the energy performance. The design of the frame especially around corner joints is important for delivering a good sealed unit.
Double or Triple Glazed
Triple glazed would give a higher level of insulation over double glazed.
Argon Gas Filled
Another way to make your windows more efficient is to use an insulating gas like Argon between the panes of your double or triple glazed windows. These gases are bad conductors preventing heat loss.
Comparison of Window U-Values (Complete window unit)
Basic Modern Double Glazed – 2.20
Energy Rated Double Glazed – 1.70
High Grade Timber Triple Glazed – 1.25 (imported Swedish model)
Gas Filled High Grade Timber Triple Glazed – 0.90
As with all purchasing decisions cost and budget will have an impact on the product that you choose and the window sellers should assist you with working out a payback in relation to opting for an upgraded spec. Don’t be afraid to ask questions and look for proof of Energy Rating certification to back up any claims made by the manufacturers.
If you are in an old home with single glazed draughty windows you can save as much as 20% on your annual heating bills by replacing your windows and doors to double or triple glazing. Grants may be available towards the cost of upgrading your windows so please contact the Sustainable Energy Authority - they will be able to tell you what grants might be available for replacing windows.
 |
